The Energy Department is ending required polygraph tests for thousands of workers at its nuclear weapons facilities, including most scientists at the government's national research labs.

The department no longer will require polygraph tests as part of a general screening of new applicants, or automatically for employees in areas of high security. Tests will be required for narrow purposes where there is specific cause, the department said.

Applicants still will undergo broad security reviews, as will current workers on a periodic basis. But, with narrow exceptions, these workers will no longer automatically be subject to a lie detector test, department officials said.

The new requirements, to go into effect Oct. 30, "will significantly reduce the number of individuals who will undergo polygraph examinations," the department said in a summary printed in the Federal Register.

The widespread use of polygraphs at federal nuclear weapons labs and elsewhere within the Energy Department has been the subject of intense resentment, especially among scientists at the national laboratories.

Critics of the polygraph program have argued that it has kept good scientists from working at federal labs, such as Lawrence Livermore in California and Los Alamos in New Mexico, and caused others to quit.

There are an estimated 20,000 high-risk security positions at the Energy Department and among its contractors that under the old rules have been routinely subject to polygraphs, according to the department.

Officials could not provide numbers Wednesday on how many workers will still be subject to polygraphs under the new criteria.

But the new rules say mandatory polygraphs would be limited to workers whose jobs require them to work with or in other agencies that require polygraphs; those where there is "a specific indication" of a clandestine relationship with a foreign country, organization or terrorist group; and those where a test is ordered in response to a specific incident of concern.

The department said a polygraph may also be administered as part of random counterintelligence evaluations.

"This is a significant retreat from the (more widespread) use of the polygraph," said Steven Aftergood, director of the project on government secrecy at the Federation of American Scientist.

"DOE deserves credit for responding to the scientific critique and employee concerns" about the uncertainties surrounding polygraph tests, Aftergood said, adding that's not been the case at some other government agencies including the FBI and intelligence community.

In fact, earlier this week, the FBI and U.S. Secret Service won a legal victory when a federal judge ruled those two agencies could continue to use polygraphs for across-the-board screening of prospective employees.

The Energy Department rejected a call by representatives of some DOE scientists and others to stop using polygraph tests altogether. Critics of the technology long have argued that such tests are not reliable and can ruin a person's career if erroneously interpreted by technicians.

Congress responded to a series of security concerns, mainly at the Los Alamos National Laboratory in New Mexico, in the late 1990s and required the Energy Department to expand its use of polygraph tests on workers in high-security jobs.

The call for greater polygraph use was enflamed by the alleged espionage scandal surrounding Los Alamos computer scientist Wen Ho Lee. Lee, who was under investigation for years, was never charged with espionage and eventually was largely exonerated.

Responding to the Lee case and a string of unrelated security lapses, Congress in 1999 directed the department to use polygraphs as a broad screening tool for high-security workers including scientists at the national labs. That brought outrage from some weapons lab workers, who argued that polygraphs were not needed to assure security and were hurting morale.

In 2002, a National Academy of Sciences study said that polygraphs should not be used as the sole reason for judging an applicant for employment. The study said it should be only used in conjunction with a broader review.

As a result, Congress directed the Energy Department to revamp its policy on polygraph use and take into account the NAS findings, resulting in the revised regulations that will go into effect at the end of this month.